Effect of manure and mineral fertilisation on pepper nutritional quality

BACKGROUND: The influence of farming systems on fruit quality remains controversial and the different aspects associated with each agricultural management system need to be studied separately to elucidate any specific effect on fruit quality. To this end, a greenhouse experiment was conducted to examine the effect of the usual fertilisation guidelines for pepper cultivation on the nutritional quality of fruits (sugars, vitamin C, total phenolic compounds, chlorophylls, total carotenoids and antioxidant activities in the hydrophilic (HAA) and lipophilic (LAA) fractions). Treatments included manure amendment combined with synthetic fertiliser applied at the rates recommended for organic (T1), low‐input (T2) and conventional (T3) practices. RESULTS: Pepper composition was not affected by increasing mineral fertilisation. In addition, treatment had no significant effect on HAA or LAA. The antioxidant activity of both the hydrophilic and lipophilic fractions increased from the green to the red stage of ripening. HAA contributed about 80% of the total antioxidant activity. CONCLUSION: Pepper response to mineral fertilisation seems to be less pronounced than that of other fruits, since antioxidant concentrations did not increase with increasing fertiliser application. Antioxidant activity in pepper was mainly linked to hydrophilic compounds (vitamin C and phenolic compounds). Ripening was the most important factor determining the fruit antioxidant composition. Copyright © 2009 Society of Chemical Industry     

Pepper antioxidant composition as affected by organic,low‐input and soilless cultivation

BACKGROUND: The aim of this work was to study the effects of organic (O), low‐input (LI) and soilless (SL) cultivation on pepper nutritional quality and antioxidant activity. For that, 24 commercial greenhouses were selected following strict criteria in order to reduce the influence of environmental conditions and realistically reflect commercial production systems. Fruits were harvested at two maturity stages (green and red) and three harvesting times during two consecutive years. RESULTS: Pepper antioxidant activity mainly stemmed from water‐soluble compounds, including organic acids and phenolic compounds. Only some differences in sugars and malic and citric acid concentrations were detected between the O and LI systems. Sugars, phenolic compounds, ascorbic acid and hydrophilic antioxidant activity were higher in the SL system. In spite of these differences, overall differences between harvesting times or between years were far greater than those due to the cropping system. CONCLUSION: The main differences in the nutritional quality of pepper fruits were observed between the soil (O and LI) and SL (the most favourable) systems. The results highlight the importance of comparing different harvesting times and years in order to study the effect of cropping system on a specific crop. Copyright © 2009 Society of Chemical Industry     

Influence of 1-Methylcyclopropene (1-MCP) on Postharvest Storage Quality in Green Bell Pepper Fruit

The goal of this research was to evaluate the efficiency of 1-methylcyclopropene (1-MCP) on maintaining the quality parameters and antioxidant activity of bell pepper cv. Selika (an original red cultivar) and cv. H1530 (??ever-green?? line) after 18?days storage at 7°C and 3?days at 20°C. Fruits were harvested at green color, from a commercial shade net house in the desert region in Israel. In both cultivars, 600?nL?L^?1 1-MCP reduced weight loss and maintained firmness more than control or 900?nL?L^?1 1-MCP. Overall, 1-MCP treatment had a pronounced effect on delaying ripening processes as shown by inhibiting color changes, decreasing decay, and maintaining quality of non-climacteric green pepper fruit. 1-MCP treatment reduced the lipophilic antioxidant activity of this fruit, but the hydrophilic antioxidant activity remained similar to that observed at harvest.     

Pepper mineral composition and sensory attributes as affected by agricultural management

BACKGROUND: Given the contradictory information available concerning the potential beneficial effects of organic production on food quality, there is a need for studies that determine the real effect of cropping systems on fruit quality. A two‐year farm study was therefore conducted to assess differences in the mineral composition and sensory quality of pepper (Capsicum annuum L. cv. Quito) fruits cultivated in organic (O), low‐input (LI) and soilless (SL) systems. Twenty‐four greenhouses were selected following strict criteria in order to reduce the influence of environmental conditions and accurately and realistically reflect commercial production systems. RESULTS: The soil (O and LI) systems provided higher Ca and Mg concentrations than the SL system. In addition, fruit colour was favourably evaluated in green and red peppers from both soil systems. In contrast, SL fruits showed higher firmness in the green stage (related to higher flesh thickness). All fruit parameters that were affected by the cropping system were also affected by the harvesting time. CONCLUSION: The main differences as regards the mineral composition and sensory attributes of the resulting fruit were observed between the soil (O and LI) and SL systems. The benefits of O peppers with respect to LI fruits could only be described as an absence of pesticide residues. Harvesting time can affect fruit composition and quality to a greater extent than cropping system. Copyright © 2009 Society of Chemical Industry     

Sustainable nitrogen fertilisation in sweet pepper: assessing growth and fruit quality and the potential nitrate pollution from different organic manures

BACKGROUND: The use of organic cultivation with manures does not avoid the risk of high nitrate concentrations if nutrient management is inefficient. So we studied the influence of three organic manures combined or not with additional chemical fertilisers on growth and yield of sweet pepper (Capsicum annuum L.), and on the soil and plant N concentrations. RESULTS: After 3 years of organic cultivation, poultry manure caused the highest soil pollution. The evolution of nitrate and organic matter in soil showed a pattern close to that of plant growth. The addition of mineral fertiliser increased vegetative growth and yield, and a cumulative season effect was observed. In treatments with no additional mineral fertiliser N translocation from leaves to fruits happened. A cumulative effect of seasons on fruit quality and a reduction near to 30% was observed in the first fruit quality category after 3 years. The fruit vitamin C content was reduced by increasing N fertilisation. CONCLUSION: The effects of organic fertiliser on soil and plant growth and yield depended on the type of manure used, its rate, and consecutive crop seasons. Horse manure gave the best combination of agricultural and environmental characteristics and could be used without additional fertigation. © 2012 Society of Chemical Industry     

Changes in the contents of antioxidant compounds in pepper fruits at different ripening stages,as affected by salinity

The interest in the consumption of pepper fruits (Capsicum annuum L.) is, to a large extent, due to its content of bioactive nutrients and their importance as dietary antioxidants. A greenhouse experiment was carried out to determine the effects of salinity and different ripening states of pepper fruits on several compounds with antioxidant properties. Fruits from plants grown under three saline treatments (0, 15, and 30 mM NaCl) were collected at three maturity states (green, turning, and red). Antioxidant activity in the hydrophilic (HAA) and lipophilic (LAA) fractions, lycopene, β-carotene, ascorbic acid, total phenolic compounds and reducing sugars were determined. From the nutritional point of view, the red state was the most appropriate state of maturation, since red peppers had the highest levels of lycopene, β-carotene, and sugars and the highest antioxidant activity for both hydrophilic and lipophilic fractions. The effect of salinity depended on the maturity state of the peppers: it had no effect on HAA, β-carotene or sugars, but decreased ascorbic acid and total phenolic compounds, and increased LAA and lycopene. The use of a moderately-saline water was beneficial when peppers were harvested in the red state, by increasing HAA and LAA in fruits, with no significant effects on other parameters.     

Effect of conventional and organic production systems on the yield and quality of field tomato cultivars grown in Tunisia

BACKGROUND: The agricultural production system and cultivation practices are critical factors in determining yield and food nutritional quality. Controversy remains regarding whether or not organic foods have a nutritional advantage when compared with their conventionally produced counterparts. In this study the effect of conventional and organic production systems on yield, physicochemical and nutritional properties of four field tomato cultivars (Perfectpeel, Rio Grande, Hypeel 108 and Firenze) was determined. In the organic system, different fertiliser combination treatments were used. RESULTS: When production system data were combined, marketable yield was not affected by cultivar. When averaged across cultivars, organic yield was about 63% of conventional yield. The production system affected fruit soluble solids, pH, titratable acidity and firmness only in some cultivars. However, no effect was found on lycopene and total phenolics in all cultivars. In the organic system, fertiliser combination treatments affected tomato yield of Rio Grande and fruit quality of Firenze and Hypeel 108. A general trend of higher quality data was obtained by using mixed compost C2 combined with its extract and codahumus 20. CONCLUSION: The production system affects tomato yield and some fruit quality attributes. The effect on fruit quality varies among cultivars, thus highlighting the need to use a range of varieties in this kind of study. Copyright © 2009 Society of Chemical Industry     

Antioxidant activity evaluation of alkyl hydroxytyrosyl ethers,a new class of hydroxytyrosol derivatives

The antioxidant activity of a new series of alkyl hydroxytyrosyl ethers was evaluated by the Rancimat test in a lipophilic food matrix and by the FRAP, ABTS and DPPH assays in a hydrophilic medium, and compared to free hydroxytyrosol (HTy), butylhydroxytoluene (BHT) and α-tocopherol. All methods used to assess the antioxidant activity of the new compounds emphasised the importance of the ortho-diphenolic structure on the maintenance of the high antioxidant activity associated with free HTy. The results obtained support the ‘polar paradox’ since the antioxidant activity of the lipophilic hydroxytyrosyl ethers was slightly lower in bulk oils and higher in hydrophilic media in comparison with their reference HTy. Although the length of the alkyl chain did not significantly affect the antioxidant activity in bulk oils, it did have a positive influence in hydrophilic medium for ethers with a short alkyl chain (methyl, ethyl and propyl), while ethers with longer alkyl chain (butyl, hexyl, octyl, dodecyl and octadecyl) maintained or even decreased their antioxidant activity, probably due to the steric effect of the side chains. In conclusion, these results show the strong antioxidant activity of a new group of lipophilic HTy derivatives that satisfies the food industry demands for new antioxidants with potential use as functional ingredients to improve the quality and nutritional properties of foods.     

Yield and baking quality of winter wheat cultivars in different farming systems of the DOK long‐term trial

BACKGROUND: A challenge in wheat (Triticum aestivum L.) breeding for organic farming is to provide high‐yielding cultivars with appropriate baking qualities under the limiting conditions of organic fertiliser input and without the use of pesticides. Cultivars are usually tested on organic and conventional farms. However, field properties may differ owing to spatial variations of soils and microclimate heterogeneity. In this study, old, organically bred and conventionally bred cultivars were tested in organic and conventional farming systems of the DOK long‐term system comparison trial. RESULTS: Effects of cultivars and systems on yield and quality parameters were statistically significant. Genotype × system interactions were generally not observed. Grain yield across all cultivars increased from 4.2 Mg ha^?1 under organic conditions up to 6.8 Mg ha^?1 under conventional conditions, with protein contents of 90 and 117 g kg^?1 respectively. Conventionally bred cultivars yielded significantly more under conventional conditions than organically bred cultivars, whereas neither organically nor conventionally bred cultivars performed better under organic conditions. CONCLUSION: Breeding for yield was successful, but only under high‐input conditions, where these successes were accompanied by rising inputs of external resources. The results of this study suggest that cultivar testing in long‐term system comparisons can complement standard on‐farm testing. Copyright © 2009 Society of Chemical Industry     

Influence of conventional and organic agricultural practices on the phenolic content in eggplant pulp: Plant-to-plant variation

Consumer awareness, pesticide and fertiliser contaminations, and environmental concerns have resulted in significant demand for organically grown farm products. The present study evaluates the influence that organic and conventional farming practices exert on the total phenolic content in eggplant samples from two cultivars, Blackbell (American eggplant) and Millionaire (Japanese eggplant), grown by conventional and organic farming practices with similar climatic conditions. In addition, plant-to-plant variation in phenolic content was determined from eight eggplant samples collected from different plants grown at various field positions. Samples were separately assayed for phenolic content by the two independent procedures, HPLC/LC–MS and Folin–Ciocalteu assay. The results of the HPLC analysis showed significant plant-to-plant variation (% RSD ranged from 22% to 48%) in 5-caffeoylqunic acid content (the most abundant phenolic acid) in eight eggplant samples collected from eight different plants belonging to the same cultivar and grown under similar conditions. The cv. Millionaire showed a higher total phenolic content compared to the Blackbell cultivar. We did not observe significant consistent trend in the phenolic content of eggplant samples grown with organic and conventional farming practices with both eggplant cultivars. We, however, observed a strong correlation (R² = 0.87) between total phenolic content as assayed by Folin–Ciocalteu assay and 5-caffeoylqunic acid, a major phenolic acid in eggplant extract. This study concludes that multiple repetitive analyses of plant products collected from different plants grown over various time periods (seasons) at different locations should always be carried to unambiguously prove the impact of growing conditions on phenolic content or antioxidant activity.     

Micronutrient contents in organic and conventional tomatoes (Solanum lycopersicum L.)

Organic food is associated by the general public with improved nutritional properties, and this has led to increasing demand for organic vegetables. The objective of this study was to investigate whether there were any differences in the micronutrient contents in organic and conventional tomatoes (Solanum lycopersicum L.). Two tomato cultivars ‘Lladó’ and ‘Antillas’ grown organically and conventionally were compared regarding their micronutrient in terms of K, Ca, Na, Mg, Fe, Zn, Mn, Cu, lycopene, ß‐carotene, ascorbic, malic and citric acids, and total phenolic compound content. Cultivar ‘Lladó’ had the highest concentration of the nutrient lycopene, ß‐carotene, Fe, Zn, Mn and Cu. Where cultivation method affected the concentration of ascorbic acid and Mn, only one cultivar was affected. For all nutrients examined, cultivar differences were greater than differences because of cultivation method. This study confirms that the most important variable in the micronutrient content of tomatoes is cultivar; organically grown tomato is no more nutritious than conventionally grown tomato when soil fertility is well managed.     

Phenolic profile,antioxidant and antiproliferative activity of black and red currants (Ribes spp.) from organic and conventional cultivation

The effect of cultivation system on phenolic profile, antioxidant capacity and antiproliferation activity in black and red currants was evaluated. Results from this study showed that Ribes fruit grown in organic system posses significantly higher total phenolics, especially anthocyanins, and antioxidant activity (DPPH and FRAP) than fruit grown in conventional system. Phenolic compounds were systematically identified and characterised by UPLC/MS Q‐TOF. The mean value of total polyphenol content in organically grown currants was similar but statistically higher compared with the conventional cultivation (11831.0 and 1543.0 mg/kg of d.m., respectively). The total values of the anthocyanins in ‘Ben Hope’, ‘Ben Alder’, ‘Titania’ and ‘Rondom’ from organic and conventional farms were 1044.5 vs. 1012.4; 1568.3 vs. 1260.4; 1417.2 vs. 1382.2; and 51.8 vs. 57.9 mg kg^?1 of d.m., respectively. Conventionally grown red currant had higher anthocyanin content than organically grown red currant (11.8%) but, however, organic fruits of red currant had 2.7 times higher content of oligomeric procyanidins than fruits coming from conventional cultivation. DPPH radical scavenging activity of currant varied from 28.29 to 37.08 mmol Trolox kg^?1 (mean 31.20) for organic fruits and from 12.67 to 31.18 mmol Trolox kg^?1 (mean 25.76) for conventional fruits. Moreover, all currants from organic cultivation possess higher ferric reducing capacity than conventionally grown fruits. It appeared that extracts of red Ribes cv. ‘Rondom’ coming from organic cultivation revealed stronger antiproliferative effect in comparison with conventional cultivation. However, a similar profile of activity was observed for ‘Ben Hope’, ‘Ben Alder’ and ‘Titania’ independently of the type of cultivation. These results indicate that the cultivation technique had important effect on the ranking of the cultivar systems.     

Is there any difference between the phenolic content of organic and conventional tomato juices?

The present study aims to compare the phenolic and hydrophilic antioxidant profiles of organically and conventionally produced tomato juices. Comparisons of analyses of archived samples from conventional and organic production systems demonstrated statistically higher levels (P < 0.05) of phenolic compounds in organic tomato juices. This increase corresponds not only with increasing amounts of soil organic matter accumulating in organic plots but also with reduced manure application rates once soils in the organic systems had reached equilibrium levels of organic matter. Using principal component analysis, results show that phenolic compounds and hydrophilic antioxidant capacity were responsible for the differentiation between organic and conventional tomato juices. Thus, there appear to be genuine differences in the bioactive components of organic and conventional tomato juices not previously reported.     

Characterisation of antioxidant compounds in sweet bell pepper (Capsicum annuum L.) under organic and conventional growing systems

BACKGROUND: Sweet red bell pepper is one of the best sources of ascorbic acid and carotenoids as well as phenolic compounds important in the human diet. There have been some studies showing a higher level of bioactive compounds in organic bell pepper fruits compared with conventional fruits, but not all studies have been consistent in this respect. The levels of carotenoids and phenolics are very variable and may be affected by ripeness, genotype and cultivation. RESULTS: The results obtained in this study showed that an organic growing system affected the level of bioactive compounds (carotenoids and polyphenols) in sweet bell pepper fruits cultivated in Poland. Organic bell pepper fruits contained significantly more dry matter, vitamin C, total carotenoids, β‐carotene, α‐carotene, cis‐β‐carotene, total phenolic acids (as well as individual gallic and chlorogenic acids) and flavonoids (quercetin D ‐glucoside, quercetin and kaempferol) compared with conventional fruits. The bell pepper variety also affected the level of antioxidant compounds in fruits. CONCLUSION: Organic growing increased the level of antioxidant compounds such as carotenoids, phenolic compounds and vitamin C in sweet bell pepper. The second significant factor affecting the antioxidant compound content of sweet bell pepper was variety. It would be necessary to continue this study as a long‐term experiment in order to eliminate the influence of seasonality. Copyright © 2012 Society of Chemical Industry     

Influence of Ca2+, K+ and NO3− fertilisation on nutritional quality of pepper

A study was conducted in order to assess the effect of different fertilisation levels of Ca²⁺, K⁺ and NO₃^? on the bioactive nutrient content in red pepper (Capsicum annuum L) fruits. The experiment was carried out in a greenhouse, under hydroponic culture. Lycopene, β‐carotene, vitamin C, total phenolic compound, sugar, nitrate and potassium contents and antioxidant activity were determined. Increasing Ca²⁺ and NO₃^? concentrations in the root medium increased the lycopene and β‐carotene contents in pepper. Antioxidant activity was determined in the hydrophilic (HAA) and lipophilic (LAA) fractions. HAA was increased by intermediate and high Ca²⁺ concentrations in the culture medium. However, LAA was raised only by NO₃^? treatments. Vitamin C, sugar and total phenolic acid contents were not affected by Ca²⁺ or NO₃^? treatments. K⁺ treatments had no effect on nutritional quality of pepper. An increased supply of Ca²⁺ and NO₃^? in the culture medium could constitute a useful practice for improving the nutritional attributes of pepper as well as its commercial quality. Copyright © 2004 Society of Chemical Industry     

Quality parameters and antioxidant properties in organic and conventionally grown broccoli after pre‐storage hot water treatment

BACKGROUND: Demand for broccoli has increased due to its high content of bioactive compounds. However, broccoli is a perishable commodity with a short shelf life mainly due to dehydration, yellowing and losses of bioactive compounds. Thus, efficient treatments to preserve broccoli quality are needed. RESULTS: The effect of heat treatment on senescence and antioxidant compounds evolution during storage at 20 °C was evaluated in organic and conventionally grown broccoli. Senescence evolved quickly as manifested by floral head yellowing, which was higher in conventional than in organic broccolis, but senescence was significantly delayed by heat treatment. All organic acids, including ascorbic acid, were found at higher concentrations in organic than in conventional broccoli at harvest but decreased during storage in all broccolis. Phenolic concentration and antioxidant activity (in both hydrophilic and lipophilic fractions) also decreased during storage, although these decreases were higher in conventional than in organic broccolis, and no differences were found attributable to heat treatment. CONCLUSIONS: Heat treatment was effective in delaying broccoli senescence, manifested by chlorophyll retention. In addition, organic broccoli maintained higher concentrations of bioactive compounds (ascorbic acid and phenolics) and antioxidant potential during storage than conventional broccoli, with higher potential health beneficial effects. © 2012 Society of Chemical Industry     

Analysis of organic acid content in cultivars of tomato harvested in Tenerife

The determination of organic acids in tomato samples was optimized using the HPLC method with on-line photodiode array detection, previous to extraction with 80% ethanol at room temperature and clean-up in Accell Plus QMA cartridge. The organic acids (oxalic, pyruvic, malic, citric, fumaric and ascorbic), Brix degree, acidity and pH were determined in five tomato cultivars (Dorothy, Boludo, Dominique, Thomas and Dunkan) harvested in Tenerife. There are several significant differences among cultivars in the concentration of many acids. The cultivation method, sampling period and the region of production were also considered. Citric, malic and oxalic acids were the major organic acids in all the cultivars. Some significant differences in the studied parameters were observed between the cultivars. The cultivation method and sampling period influenced in a variable way the studied parameters, depending on the tomato cultivar. The production region influenced the ascorbic acid concentration of the tomatoes. Applying stepwise discriminant analysis, it was found that the sampling period is more important in the differentiation of the tomato samples than the cultivar, cultivation method and production region.     

Postharvest evaluation of soilless-grown table grape during storage in modified atmosphere

BACKGROUND: Soilless growth systems, developed mainly for vegetables and ornamental crops, have also been used recently as an alternative to soil culture for table grape in order to achieve optimal production performance. In this study, sensory, physical and chemical parameters were analysed in table grapes obtained from soil and soilless growth systems at harvest and during storage in air or modified atmosphere. RESULTS: At harvest, soilless‐grown berries were 30% firmer than those grown in soil. Moreover, they showed 60% higher antioxidant activity and total phenol content than soil‐grown fruits. Modified atmosphere storage resulted in a better quality of table grapes compared with those stored in air. Furthermore, soilless growth was more suitable than soil growth for preserving visual quality and controlling rachis browning and weight loss. CONCLUSION: Since the soilless system produces berries that are cleaner and of higher quality than those grown in soil, the implementation of soilless growth for the production of health‐promoting and convenience fruits is suggested. Copyright © 2011 Society of Chemical Industry     

Antioxidant capacities and total phenolic contents of 56 vegetables

The antioxidant capacities and total phenolic contents of lipophilic and hydrophilic extracts of 56 commonly consumed vegetables were studied. The resulted showed that antioxidant capacities and total phenolic contents in the lipophilic fraction were higher than those in hydrophilic fraction. The different vegetables had diverse antioxidant capacities. The highest antioxidant capacities and phenolic contents were found in Chinese toon bud, loosestrife, perilla leaf, cowpea, caraway, lotus root, sweet potato leaf, soy bean (green), pepper leaf, ginseng leaf, chives, and broccoli, while the values were very low in marrow squash and eggplant (purple). Furthermore, several phenolic compounds were detected, and chlorogenic acid, gallic acid and galangin were widely found in these vegetables. The results provide support for dietary guidelines as well as epidemiological research.     

Hydrophilic and Lipophilic Antioxidant Activity in Different Leaves of Three Lettuce Varieties

Three different Lactuca sativa L. varieties (Iceberg, Romaine and Baby head) were analysed in order to determine differences in the antioxidant activity, both hydrophilic and lipophilic, and in the total phenolic content of different leaves (stem, inner, medium and outermost leaves). Romaine showed the highest level of hydrophilic and lipophilic antioxidant activity, and its phenolic content was also higher than that of Iceberg and Baby head. According to leaf position, lipophilic antioxidant activity increased sharply from stem to outermost leaves, suggesting a protective role for the lipophilic antioxidant in mature or light-exposed leaves, while hydrophilic antioxidant activity shows a non-specific distribution. The phenolic content also increased in Romaine from stem to outermost leaves, although no significant changes were observed in Iceberg or Baby head lettuces in this respect.